Gas cluster ion beam process for opening conformal layer in a high aspect ratio contact via

ABSTRACT

A method for patterning a layer at a bottom of a high aspect ratio feature of a substrate is described. The method includes providing the substrate having a first layer with a feature pattern overlying a second layer. The feature pattern is characterized with an initial critical dimension (CD), an initial corner profile, and an aspect ratio of 5:1 or greater. The method further includes etching through at least a portion of the second layer at the bottom of the feature pattern to extend the feature pattern at least partially into the second layer while retaining a final CD within a threshold of the initial CD and a final corner profile within a threshold of the initial corner profile using a gas cluster ion beam (GCIB) etching process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 13/492,094 filed Jun. 8, 2012 and entitled GAS CLUSTER ION BEAM PROCESS FOR OPENING CONFORMAL LAYER IN A HIGH ASPECT RATIO CONTACT VIA, the disclosure of which is incorporated herein by reference in its entirety as if completely set forth herein below.

FIELD OF INVENTION

The invention relates to gas cluster ion beam (GCIB) processing.

DESCRIPTION OF RELATED ART

Typically, during fabrication of an integrated circuit (IC), semiconductor production equipment utilize a (dry) plasma etch process to remove or etch material along fine lines or within vias or contacts patterned on a semiconductor substrate. The success of the plasma etch process requires that the etch chemistry includes chemical reactants suitable for selectively etching one material while etching another material at a substantially lesser rate. Furthermore, the success of the plasma etch process requires that acceptable profile control may be achieved while applying the etch process uniformly to the substrate. However, in some etch applications, conventional etch processes may not achieve acceptable profile control that is uniformly applied across the substrate.

SUMMARY OF THE INVENTION

Embodiments of the invention relate to gas cluster ion beam (GCIB) processing. In particular, embodiments of the invention relate to GCIB etch processing. Furthermore, embodiments of the invention relate to GCIB etch processing of various materials to achieve target etch process metrics.

According to one embodiment, a method for opening a conformal layer at the bottom of a contact via on a substrate is described. The method includes providing a substrate having a first layer with a via pattern formed therein and a second layer conformally deposited on the first layer and within the via pattern to establish a contact via pattern characterized by an initial mid-critical dimension (CD). The method further includes etching through the second layer at the bottom of the contact via pattern to extend the contact via pattern through the second layer and form a contact via while retaining at least part of the second layer on the top surface of the first layer, the corner at the entrance to the via pattern, and the sidewalls of the via pattern, wherein the etching is performed by irradiating the substrate with a GCIB according to a GCIB etching process.

According to another embodiment, a method for patterning a layer at a bottom of a high aspect ratio feature of a substrate is described. The method includes providing the substrate having a first layer with a feature pattern overlying a second layer. The feature pattern is characterized with an initial critical dimension (CD), an initial corner profile, and an aspect ratio of 5:1 or greater. The method further includes etching through at least a portion of the second layer at the bottom of the feature pattern to extend the feature pattern at least partially into the second layer while retaining a final CD within a threshold of the initial CD and a final corner profile within a threshold of the initial corner profile using a gas cluster ion beam (GCIB) etching process.

According to another embodiment, a method for controlling patterning a layer at a bottom of a high aspect ratio feature of a substrate is described. The method includes providing a substrate having a first layer with a feature pattern overlying a second layer. The feature pattern is characterized with an initial critical dimension (CD), an initial corner profile, and an aspect ratio of 5:1 or greater. The method further includes configuring a gas cluster ion beam (GCIB) etching process based on target etch process metrics to control the GCIB etching process to retain a final CD within a threshold of the initial CD and a final corner profile within a threshold of the initial corner profile. The method further includes etching through at least a portion of the second layer at the bottom of the feature pattern to extend the feature pattern at least partially into the second layer using the GCIB etching process configured to the target etch process metrics.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A through 1E provide schematic illustrations of methods for opening a conformal layer at the bottom of a contact via on a substrate according to an embodiment;

FIG. 2 is a flow chart illustrating a method for opening a conformal layer at the bottom of a contact via on a substrate according to an embodiment;

FIGS. 3A through 3D provide schematic illustrations of methods for patterning a layer at a bottom of a high aspect ratio feature according to an embodiment;

FIG. 4 is a flow chart illustrating a method for patterning a layer at a bottom of a high aspect ratio feature according to an embodiment;

FIG. 5A provides a schematic graphical illustration of a beam energy distribution function for a GCIB;

FIG. 5B provides a schematic graphical illustration of a beam angular distribution function for a GCIB;

FIGS. 6A through 6L graphically depict exemplary data for etching material on a substrate;

FIG. 7 is an illustration of a GCIB processing system;

FIG. 8 is another illustration of a GCIB processing system;

FIG. 9 is yet another illustration of a GCIB processing system;

FIG. 10 is an illustration of an ionization source for a GCIB processing system; and

FIG. 11 is an illustration of another ionization source for a GCIB processing system.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

Methods for etching layers, including high aspect ratio (HAR) contacts, on a substrate using gas cluster ion beam (GCIB) processing are described in various embodiments. One skilled in the relevant art will recognize that the various embodiments may be practiced without one or more of the specific details, or with other replacement and/or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention. Similarly, for purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the invention. Nevertheless, the invention may be practiced without specific details. Furthermore, it is understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, but does not denote that they are present in every embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. Various additional layers and/or structures may be included and/or described features may be omitted in other embodiments.

“Substrate” as used herein generically refers to the object being processed in accordance with the invention. The substrate may include any material portion or structure of a device, particularly a semiconductor or other electronics device, and may, for example, be a base substrate structure, such as a semiconductor wafer or a layer on or overlying a base substrate structure such as a thin film. Thus, substrate is not intended to be limited to any particular base structure, underlying layer or overlying layer, patterned or unpatterned, but rather, is contemplated to include any such layer or base structure, and any combination of layers and/or base structures. The description below may reference particular types of substrates, but this is for illustrative purposes only and not limitation.

As described in part above, etch rate, etch selectivity, profile control, including CD (critical dimension) control, and surface roughness provide, among other process results, essential metrics for determining successful pattern etching. As an example, when transferring a feature pattern into a material layer on a substrate, it is important to selectively etch one material at a rate sufficient for adequate process throughput, while controlling the pattern profile and surface roughness of pattern surfaces as well as adjacent surfaces. Furthermore, it is important to control the etch rate, etch selectivity, and etch profile uniformly for all feature patterns formed in the material layer on the substrate, and/or spatially adjust the control of these parameters for feature patterns formed in the material layer on the substrate.

As an example, etch profile control is critically important when performing a high aspect ratio (HAR) contact etch in memory structures, such as three-dimensional (3D) flash memory. During the opening of the HAR contact, conventional etch processes, such as reactive ion etch (RIE) processes, fail to produce acceptable results. In particular, RIE causes critical dimension (CD) loss for the contact via and severe corner erosion at the entrance to the contact via, either of which is unacceptable and leads to poor electrical properties once the contact is filled.

Therefore, according to various embodiments, methods for opening a conformal layer at the bottom of a contact via on a substrate are described. Also, according to various embodiments, methods for patterning a layer at a bottom of a high aspect ratio feature on a substrate are also described. Referring now to the drawings wherein like reference numerals designate corresponding parts throughout the several views, FIGS. 1A through 1E graphically depict various methods for opening a conformal layer at the bottom of a contact via. Furthermore, FIG. 2 provides a flow chart 20 illustrating a method for etching various materials on a substrate according to an embodiment.

The method illustrated in flow chart 20 begins in 21 with providing a substrate 11 having a first layer 12 with a via pattern 14 formed therein (see FIG. 1A) and a second layer 13A (see FIG. 1B) conformally deposited on the first layer 12 and within the via pattern 14. The second layer 13A conforms to the first layer 12, extends along a top surface 12A of the first layer 12, wraps over a corner 12B at an entrance 14A to the via pattern 14, and penetrates into the via pattern 14 while conforming to the sidewalls 12C and the bottom 12D of the via pattern 14 to partially establish a contact via pattern 15A. As shown in FIG. 1B, the contact via pattern 15A is characterized by an initial mid-critical dimension (CD) 16AM measured at approximately mid-depth of the contact via pattern 15A, and an initial top-CD 16AT measured at approximately the top of the contact via pattern 15A. Further, the contact via pattern 15A may be characterized by an initial corner profile 13AC for the second layer 13A as it wraps over corner 12B of via pattern 14.

The substrate 11 may include a bulk silicon substrate, a single crystal silicon (doped or un-doped) substrate, a semiconductor-on-insulator (SOI) substrate, or any other semiconductor substrate containing, for example, Si, SiC, SiGe, SiGeC, Ge, GaAs, InAs, InP, as well as other III/V or II/VI compound semiconductors, or any combination thereof (Groups II, Ill, V, VI refer to the classical or old IUPAC notation in the Periodic Table of Elements; according to the revised or new IUPAC notation, these Groups would refer to Groups 2, 13, 15, 16, respectively). Substrate 11 can be of any size, for example, a 200 mm (millimeter) substrate, a 300 mm substrate, a 450 mm substrate, or an even larger substrate.

The first layer 12 may include an oxide, such as a layer of silicon dioxide (SiO₂), or more generally, SiO_(x), wherein x is a positive real number. The first layer 12 may include a dopant or other material introduced therein. The first layer 12 may include a low dielectric constant (low-k) layer.

The second layer 13A may include an oxide-nitride-oxide (ONO) layer. For example, the second layer 13A may include a multi-layer film containing silicon oxide, silicon nitride, and silicon oxide. The second layer 13A may be deposited using one or more deposition processes. The one or more deposition processes may include chemical vapor deposition (CVD), plasma enhanced CVD, atomic layer deposition (ALD), plasma enhanced ALD, or GCIB deposition processes, or any combination of two or more thereof. The thickness of the second layer 13A may range from about 5 nm (nanometers) to about 100 nm. Alternatively, the thickness of the second layer 13A may range from about 10 nm to about 50 nm. Alternatively yet, the thickness of the second layer 13A may range from about 20 nm to about 40 nm. For example, the thickness of the second layer 13A may be about 25 nm to about 35 nm, or about 30 nm.

In 22 and as shown in FIG. 1D, the second layer 13A is etched to extend the contact via pattern 15A at the bottom 12D of the via pattern 14 through the second layer 13A and form a contact via 15C. After forming the contact via 15C, at least a portion 13C of the second layer 13A remains on the top surface 12A of the first layer 12, the corner 12B at the entrance 14A to the via pattern 14, and the sidewall 12C of the via pattern 14. The partial etching of the second layer 13A to form contact via 15C is performed by irradiating substrate 11 with a gas cluster ion beam (GCIB) according to a GCIB etching process.

The contact via 15C may be characterized by an aspect ratio of 5:1 or greater, wherein the aspect ratio is measured as the ratio between a depth of the contact via 15C following the GCIB etching process and a final mid-CD 16CM of the contact via 15C. Furthermore, the aspect ratio may be 10:1 or greater.

Furthermore, during formation of the contact via 15C, it is desirable that the CD loss in the contact via 15C and the erosion of the corner profile 13CC is kept to a minimum. As shown in FIG. 1D, the CD loss may be measured as the difference between the final mid-CD 16CM for the contact via 15C and the initial mid-CD 16AM for the contact via pattern 15A. Preferably, the CD loss has a value of 10 nm or less, and more preferably, the CD loss has a value of 5 nm or less, or 4 nm or less, or 3 nm or less, or most preferably, 2 nm or less.

Additionally, as shown in FIG. 1E, the amount of erosion at the corner 13CC may be quantified by measuring the difference between a final top-CD 16CT for the contact via 15C and the initial top-CD 16AT for the contact via pattern 15A. Preferably, the difference in top-CD has a value of 10 nm or less, and more preferably, the difference in top-CD has a value of 5 nm or less, or 4 nm or less, or 3 nm or less, or most preferably, 2 nm or less. Another measure of the performance for the GCIB etching process is the change in thickness 16CF of the second layer 13A on the top surface 12A of the first layer 12. Preferably, the change in thickness 16CF has a value of 10 nm or less. Contact via patterning can achieve the aforementioned specifications when using a GCIB etching process, as will be described in greater detail below.

However, as illustrated in FIG. 1C when using a conventional etching process, such as RIE, to extend the contact via pattern 15A through the second layer 13A and form a contact via 15B while retaining at least a portion 13B of the second layer 13A, the end result is unsatisfactory, and generally, unacceptable for current and future electronic devices. As noted in the description of the related art, profile and CD control are important parameters that conventional etch processes oftentimes cannot achieve to the satisfaction of the device maker. In particular, with contact via patterning for memory fabrication, the CD loss may be excessive, and the erosion of the corner profile 13BC at the entrance 14A to the via pattern 14 can be severe relative to the initial corner profile 13AC. In the former, the CD loss may exceed 10 nm. In the latter, the erosion of the corner profile 13BC may be such that one or more sub-layers of the ONO layer constituting the second layer 13B are penetrated, or that the second layer 13B is consumed entirely at the corner 12B, thus exposing the first layer 12. In this case, the difference between a final top-CD 16BT for the contact via 15B and the initial top-CD 16AT for the contact via pattern 15A may exceed 10 nm.

FIGS. 3A through 3D graphically depict various methods for patterning a layer at a bottom of a high aspect feature of a substrate, wherein like reference numerals designate corresponding parts throughout the several views. Furthermore, FIG. 4 provides a flow chart 60 illustrating a method for etching various materials on a substrate according to an embodiment.

With particular reference to FIGS. 3A and 4, the method illustrated in flow chart 60 begins in 61 with providing a substrate 51 having a first layer 52 with a feature pattern 54A therein overlying a second layer 53A. Thus, second layer 53A resides between the first layer 52 and the substrate 51. As shown in FIG. 3A, the feature pattern 54A is characterized with an initial mid-depth critical dimension (CD) 56AM measured at approximately mid-depth of the feature pattern 54A, an initial top-depth CD 56AT measured at approximately the top of the feature pattern 54A, and an initial bottom-depth CD 56AB measured at approximately the bottom 52D of the feature pattern 54A. At the bottom 52D of the feature pattern 54A, an initial exposed surface 54AE is presented, which may be a top surface 53AT of second layer 53A, as shown. Further, the feature pattern 54A may be characterized by an initial corner profile 52BA for the top 52A of the first layer 52 as it interfaces with the feature pattern 54A.

The feature pattern 54A may be characterized by an aspect ratio of 5:1 or greater. The aspect ratio is measured as the ratio between a depth of the feature pattern 54A and an initial mid-depth CD 56AM of the feature pattern 54A. Furthermore, the aspect ratio may be 10:1 or greater.

The substrate 51 may be of a material and size described above for the substrate 11. Similarly, the first layer 52 and second layer 53A may be of materials and thicknesses as described above for first and second layers 12 and 13A, respectively. In this embodiment, first layer 52 overlies second layer 53A, rather than second layer 13A overlying first layer 12 as in FIG. 1B, but the materials and thicknesses of the two layers may be the same or similar in each embodiment.

In 62 and as shown in FIG. 3C, the second layer 53C is etched to extend the etched feature pattern 54C to a depth beyond the initial exposed surface 54AE at the bottom 52D of the feature pattern 54A to an etched exposed surface 54CE beneath the top surface 53CT of second layer 53C, where the etched exposed surface 54CE is a bottom of the etched feature pattern 54C. The etching of the initial exposed surface 54AE in the feature pattern 54A to form feature pattern 54C is performed by irradiating the second layer 53C with a gas cluster ion beam (GCIB) according to a GCIB etching process. The GCIB process may be performed to partially or fully transfer the feature pattern 54C into the second layer 53C. As shown in FIG. 3C, the second layer is partially etched to extend the feature pattern 54C partially into the second layer 53C, i.e., to a depth less than the thickness of second layer 53A. It may be appreciated, however, that feature pattern 54C may be fully transferred into the second layer 53C to reach, and break through, a bottom surface 53CB thereof. In other words, etching is to a depth beneath the top surface 53CT sufficient to reach the bottom surface 53CB of second layer 53C and expose the underlying structure. The depth may thus be equal to the thickness of second layer 53A.

During formation of the feature pattern 54C which is at least partially extended into second layer 53C, it is desirable that the CD loss in the feature pattern 54C and the erosion of the corner profile 52BC is kept to a minimum. The CD of the feature pattern 54C and the corner profile 52BC are not degraded beyond a threshold of the CD of the feature pattern 54A and the corner profile 52BA, respectively. The threshold is a pre-determined design specification regarding the formation of the feature pattern 54C to maintain the CD loss in the feature pattern 54C and the erosion of the corner profile 52BC within the pre-determined threshold of the CD of the feature pattern 54A and the corner profile 52BA, respectively. As shown, in FIG. 3C, the CD loss may be measured as the difference between the final mid-depth CD 56CM for the feature pattern 54C and the initial mid-depth CD 56AM for the feature pattern 54A. Preferably, the CD loss of the feature pattern 54C is within a threshold value of 10 nm of less of the CD of the feature pattern 54A, and more preferably, the CD loss is within a threshold value of 5 nm or less, or 4 nm or less, or 3 nm or less, or most preferably, 2 nm or less.

Additionally, as shown in FIG. 3D, the amount of erosion at the corner profile 52BC may be quantified by measuring the difference between a final top-depth CD 56CT for the feature pattern 54C and the initial top-depth CD 56AT for the feature pattern 54A. Preferably, the difference in the initial top-depth CD 56AT and the final top-depth CD 56CT is within a threshold value of 10 nm or less, and more preferably, a value of 5 nm or less, or 4 nm or less, or 3 nm or less, or most preferably, 2 nm or less. Another measure of the performance for the GCIB etching process is the change in thickness 56CF of the top surface 52A of the first layer 52. Preferably, the change in thickness 56CF is within the threshold value of 10 nm or less. Feature patterning can achieve the aforementioned specifications when using a GCIB etching process, as will be described in greater detail below.

However, as illustrated in FIG. 3B, when using a conventional etching process, such as RIE, to extend the feature pattern 54A through at least a portion of second layer 53A, the end result is unsatisfactory, and generally, unacceptable for current and future electronic devices. As noted in the description of the related art, profile and CD control are important parameters that conventional etch processes oftentimes cannot achieve to the satisfaction of the device maker. In particular, with feature patterning for memory fabrication, the CD loss may be excessive, and the erosion of the corner profile 52BB at the entrance of the feature pattern 54B can be severe relative to the initial corner profile 52BA. In the former, the CD loss may exceed the threshold value of 10 nm. In the latter, the corner profile 52BB of the top surface 52B of the first layer 52 is consumed so that the difference between a final top-depth CD 56BT for the feature pattern 54B and the initial top-depth 56AT for the feature pattern 54A may exceed a threshold value of 16 nm. In addition, as illustrated in FIG. 3B, the CD loss of the mid-depth CD 56BM and the bottom-depth CD 56BB can also be severe relative to the respective mid-depth CD 56AM and the bottom-depth CD 56AB. The CD loss again may exceed a threshold value of 10 nm which is unsatisfactory.

To achieve the GCIB etching process and results illustrated and described in FIGS. 1A, 1B, 1D, 1E, 2, 3A, 3C, 3D, and 4, the GCIB etching process includes disposing a substrate, such as substrate 11, within a gas cluster ion beam (GCIB) processing system, and maintaining a reduced-pressure environment around a substrate holder for holding the substrate in the GCIB processing system. The GCIB processing system may include any one of the GCIB processing systems (100, 100′ or 100″) described below in FIG. 7, 8 or 9, or any combination thereof.

The GCIB etching process proceeds with holding the substrate 11 securely within the reduced-pressure environment of the GCIB processing system. The temperature of substrate 11 may or may not be controlled. For example, substrate 11 may be heated or cooled during a GCIB pre-treatment, etching, or post-treatment process.

When performing the GCIB etching process, one or more target etch process metrics are selected. As noted above and discussed in greater detail below, the target etch process metrics may include an etch rate of the first layer, an etch rate of the second layer, an etch rate of the substrate, an etch selectivity between the first layer and the second layer, an etch selectivity between the second layer and the substrate, a surface roughness of the second layer, a surface roughness of the substrate, an etch profile of the contact via, a CD of the contact via, and a corner profile of the contact via. One or more GCIB properties of a GCIB process condition may be set for operating the GCIB processing system to perform the GCIB etching process and achieve the one or more target etch process metrics. In addition to etch process metrics, other metrics may be used, including electrical test metrics following completion of the contact fill.

In the GCIB processing system, a gas cluster ion beam (GCIB) is formed from a pressurized gas containing at least one etching gas. The at least one etching gas may include a halogen element. The at least one etching gas may include a halogen element and one or more elements selected from the group consisting of C, H, N, and S.

For example, the at least one etching gas may include F₂, Cl₂, Br₂, NF₃, or SF₆. Additionally, for example, the at least one etching gas may include a halide, such as HF, HCl, HBr, or HI. Furthermore, for example, the at least one etching gas may include a halomethane, such as a mono-substituted halomethane (e.g., CH₃F, CH₃Cl, CH₃Br, CH₃I), a di-substituted halomethane (e.g., CH₂F₂, CH₂ClF, CH₂BrF, CH₂F₁, CH₂Cl₂, CH₂BrCl, CH₂Cl₁, CH₂Br₂, CH₂BrI, CH₂I₂), a tri-substituted halomethane (e.g., CHF₃, CHClF₂, CHBrF₂, CHF₂I, CHCl₂F, CHBrClF, CHClFI, CHBr₂F, CHBrFI, CHFI₂, CHCl₃, CHBrCl₂, CHCl₂I, CHBr₂Cl, CHBrClI, CHCl₂, CHBr₃, CHBr₂I, CHBrI₂, CHI₃), or a tetra-substituted halomethane (e.g., CF₄, CClF₃, CBrF₃, CF₃I, CCl₂F₂, CBrClF₂, CClF₂I, CBr₂F₂, CBrF₂I, CF₂I₂, CCl₃F, CBrCl₂F, CCl₂FI, CBr₂CIF, CBrClFI, CClFI₂, CBr₃F, CBr₂FI, CBrFI₂, CFI₃, CCl₄, CBrCl₃, CCl₃I, CBr₂Cl₂, CBrCl₂I, CCl₂I₂, CBr₃CI, CBr₂CII, CBrCl₁₂, CCII₃, CBr₄, CBr₃I, CBr₂₁₂, CBrI₃, Cl₄).

To form the GCIB, constituents of the etching gas should be selected that exist in a gaseous phase either alone or in combination with a carrier gas (e.g., a noble gas element or nitrogen) at relatively high pressure (e.g., a pressure of one atmosphere or greater).

In one embodiment, when etching a Si-containing and/or Ge-containing material, the at least one etching gas includes a halogen element selected from the group consisting of F, CI, and Br. The at least one etching gas may further include C, or H, or both C and H. For example, the at least one etching gas may include a halide or a halomethane. Additionally, for example, the at least one etching gas may include SF₆, NF₃, F₂, Cl₂, Br₂, HF, HCl, HBr, CClF₃, CBrF₃, CHClF₂, or C₂CIF₅, or any combination of two or more thereof.

In another embodiment, when etching a Si-containing and/or Ge-containing material, the at least one etching gas includes two different halogen elements. A first halogen element may be selected from the group consisting of Cl and Br, and the second halogen element may include F. The at least one etching gas may further include C, or H, or both C and H. For example, the at least one etching gas may include a halomethane. Additionally, for example, the at least one etching gas may include CClF₃, CBrF₃, CHClF₂, or C₂CIF₅, or any combination of two or more thereof.

In another embodiment, when etching a Si-containing material having Si and one or more elements selected from the group consisting of O, C, N, and Ge, the at least one etching gas includes C, H, and a halogen element. For example, the etching gas may include a halomethane. Additionally, for example, the etching gas may include CH₃F, CH₃Cl, CH₃Br, CHF₃, CHClF₂, CHBrF₂, CH₂F₂, CH₂ClF, CH₂BrF, CHCl₂F, CHBr₂F, CHCl₃, CHBrCl₂, CHBr₂Cl, or CHBr₃, or any combination of two or more thereof.

In another embodiment, when etching an ONO layer to pattern a HAR contact via, the etching gas may include CHF₃. In another embodiment, when etching an ONO layer to pattern a HAR contact via, the etching gas may include CHF₃ and an oxygen-containing gas. The oxygen-containing gas may include O₂, CO, CO₂, NO, NO₂, or N₂O. In yet another embodiment, when etching an ONO layer to pattern a HAR contact via, the etching gas may include CHF₃ and O₂. A CHF₃-based GCIB etching process can achieve the target etch process metrics noted above.

The at least one etching gas may include a first etching gas and a second etching gas. In one embodiment, the first etching gas contains CI or Br, and the second etching gas contains F. For example, the first etching gas may contain Cl₂, and the second etching gas may contain NF₃. In another embodiment, the first etching gas contains a halomethane or halide, and the second etching gas contains F, CI, or Br. In another embodiment, the first etching gas contains C, H, and a halogen element, and the second etching gas contains F, CI, or Br. For example, the first etching gas may contain CHF₃, CHCl₃, or CHBr₃, and the second etching gas may contain NF₃ or Cl₂. The first etching gas and the second etching gas may be continuously introduced to the GCIB. Alternatively, the first etching gas and the second etching gas may be alternatingly and sequentially introduced to the GCIB.

The pressurized gas may further include a compound containing a halogen element; a compound containing F and C; a compound containing H and C; or a compound containing C, H, and F, or any combination of two or more thereof. Additionally, the pressurized gas may further include a chlorine-containing compound, a fluorine-containing compound, or a bromine-containing compound. Additionally, the pressurized gas may further include a compound containing one or more elements selected from the group consisting of C, F, H, CI, and Br. Additionally yet, the pressurized gas may further include a silicon-containing compound, a germanium-containing compound, a nitrogen-containing compound, an oxygen-containing compound, or a carbon-containing compound, or any combination of two or more thereof. Furthermore, the pressurized gas may further include one or more elements selected from the group consisting of B, C, H, Si, Ge, N, P, As, O, S, F, CI, and Br. Further yet, the pressurized gas may further include He, Ne, Ar, Kr, Xe, O₂, CO, CO₂, N₂, NO, NO₂, N₂O, NH₃, F₂, HF, SF₆, or NF₃, or any combination of two or more thereof.

Even further yet, the GCIB may be generated from a pressurized gas that includes at least one dopant, or film forming constituent for depositing or growing a thin film, or any combination of two or more thereof.

In another embodiment, the GCIB may be generated by alternatingly and sequentially using a first pressurized gas containing an etch gas and a second pressurized gas containing a film forming gas. In yet other embodiments, a composition and/or a stagnation pressure of the GCIB may be adjusted during the etching.

As noted above, one or more GCIB properties of a GCIB process condition for the GCIB are set to achieve the one or more target etch process metrics. To achieve the target etch process metrics noted above, such as etch rate, etch selectivity, surface roughness control, profile control, etc., the GCIB may be generated by performing the following: selecting a beam acceleration potential, one or more beam focus potentials, and a beam dose; accelerating the GCIB according to the beam acceleration potential; focusing the GCIB to according to the one or more beam focus potentials; and irradiating the accelerated GCIB onto at least a portion of the substrate according to the beam dose.

Furthermore, in addition to these GCIB properties, a beam energy, a beam energy distribution, a beam angular distribution, a beam divergence angle, a stagnation pressure, a stagnation temperature, a mass flow rate, a cluster size, a cluster size distribution, a beam size, a beam composition, a beam electrode potential, or a gas nozzle design (such as nozzle throat diameter, nozzle length, and/or nozzle divergent section half-angle) may be selected. Any one or more of the aforementioned GCIB properties can be selected to achieve control of target etch process metrics, such as those noted above. Furthermore, any one or more of the aforementioned GCIB properties can be modified to achieve control of target etch process metrics, such as those noted above.

In FIG. 5A, a schematic graphical illustration of a beam energy distribution function for a GCIB is illustrated. For example, FIG. 5A graphically illustrates several beam energy distributions (30A, 30B, 30C, 30D), wherein the peak beam energy decreases and the energy distribution broadens as one proceeds through the distributions in direction 35.

The beam energy distribution function for the GCIB may be modified by directing the respective GCIB along a GCIB path through an increased pressure region such that at least a portion of the GCIB traverses the increased pressure region. The extent of modification to the beam energy distribution may be characterized by a pressure-distance (d) integral along the at least a portion of the GCIB path. When the value of the pressure-distance integral is increased (either by increasing the pressure and/or the path length (d)), the beam energy distribution is broadened and the peak energy is decreased. When the value of the pressure-distance integral is decreased (either by decreasing the pressure and/or the path length (d)), the beam energy distribution is narrowed and the peak energy is increased. As an example, one may broaden the beam energy distribution to increase the beam divergence, or one may narrow the beam energy distribution to decrease the beam divergence.

The pressure-distance integral along the at least a portion of the GCIB path may be equal to or greater than about 0.0001 torr-cm. Alternatively, the pressure-distance integral along the at least a portion of the GCIB path may be equal to or greater than about 0.001 torr-cm. Alternatively yet, the pressure-distance integral along the at least a portion of the GCIB path may be equal to or greater than about 0.01 torr-cm. As an example, the pressure-distance integral along the at least a portion of the GCIB path may range from 0.0001 torr-cm to 0.01 torr-cm. As another example, the pressure-distance integral along the at least a portion of the GCIB path may range from 0.001 torr-cm to 0.01 torr-cm.

Alternatively, the beam energy distribution function for the GCIB may be modified by modifying or altering a charge state of the respective GCIB. For example, the charge state may be modified by adjusting an electron flux, an electron energy, or an electron energy distribution for electrons utilized in electron collision-induced ionization of gas clusters.

In FIG. 5B, a schematic graphical illustration of a beam angular distribution function for a GCIB is illustrated. For example, FIG. 5B graphically illustrates a first beam angular distribution function 40 characterized by a first peak 42 at a direction of incidence 45 (i.e., relative angle is 0°) and a first width 44 (e.g., a full-width at half maximum (FWHM)). Additionally, for example, FIG. 5B illustrates a second beam angular distribution function 40′ characterized by a second peak 42′ at the direction of incidence 45 (i.e., relative angle is 0°) and a second width 44′ (e.g., a full-width at half maximum (FWHM)). The first beam angular distribution function 40 represents a narrow distribution (or a relatively narrower beam divergence angle), while the second beam angular distribution function 40′ represents a relatively broader distribution (or a relatively broader beam divergence angle). Hence, the directionality of the GCIB relative to normal incidence on the substrate may be adjusted by altering the beam angular distribution function (e.g., changing the angular distribution between the first beam angular distribution function 40 and the second beam angular distribution function 40′). The beam angular distribution function or beam divergence angle may be modified using the aforementioned techniques described for modifying the beam energy distribution function.

In one embodiment, the one or more GCIB properties of the GCIB process condition may include a GCIB composition, a beam dose, a beam acceleration potential, a beam focus potential, a beam energy, a beam energy distribution, a beam angular distribution, a beam divergence angle, a flow rate of said GCIB composition, a stagnation pressure, a stagnation temperature, a background gas pressure for an increased pressure region through which said GCIB passes, or a background gas flow rate for an increased pressure region through which said GCIB passes (e.g., a pressure cell (P-Cell) value, as will be discussed in greater detail below).

In another embodiment, the setting of the one or more GCIB properties to achieve the one or more target etch process metrics may include setting a GCIB composition, a beam acceleration potential, a flow rate of the GCIB composition, and a background gas flow rate for an increased pressure region through which the GCIB passes to achieve two or more of a target etch rate for the first material and/or the second material, a target etch selectivity between the first material and the second material, and a target surface roughness for the first material and/or the second material.

As will be shown below, the one or more GCIB properties may be adjusted to alter the target etch selectivity between the first and second materials to values less than unity, substantially near unity, and above unity. Furthermore, as will be shown below, the one or more GCIB properties may be adjusted to alter the target surface roughness for the first material and/or the second material to values less than or equal to 5 Angstrom. Further yet, the one or more GCIB properties may be adjusted to achieve a relatively high etch rate condition for the first and/or second materials, or achieve a relatively low etch rate condition for the first and/or second materials.

When using the pressure cell, the GCIB may be accelerated through the reduced pressure environment towards the substrate according to a beam acceleration potential. For the GCIB, the beam acceleration potential may range up to 100 kV, the beam energy may range up to 100 keV, the cluster size may range up to several tens of thousands of atoms, and the beam dose may range up to about 1×10¹⁷ clusters per cm². For example, the beam acceleration potential of the GCIB may range from about 1 kV to about 70 kV (i.e., the beam energy may range from about 1 keV to about 70 keV, assuming an average cluster charge state of unity). Additionally, for example, the beam dose of the GCIB may range from about 1×10¹² clusters per cm² to about 1×10¹⁴ clusters per cm².

The GCIB may be established having an energy per atom ratio ranging from about 0.25 eV per atom to about 100 eV per atom. Alternatively, the GCIB may be established having an energy per atom ratio ranging from about 0.25 eV per atom to about 10 eV per atom. Alternatively, the GCIB may be established having an energy per atom ratio ranging from about 1 eV per atom to about 10 eV per atom.

The establishment of the GCIB having a desired energy per atom ratio may include selection of a beam acceleration potential, a stagnation pressure for formation of the GCIB, or a gas flow rate, or any combination thereof. The beam acceleration potential may be used to increase or decrease the beam energy or energy per ion cluster. For example, an increase in the beam acceleration potential causes an increase in the maximum beam energy and, consequently, an increase in the energy per atom ratio for a given cluster size. Additionally, the stagnation pressure may be used to increase or decrease the cluster size for a given cluster. For example, an increase in the stagnation pressure during formation of the GCIB causes an increase in the cluster size (i.e., number of atoms per cluster) and, consequently, a decrease in the energy per atom ratio for a given beam acceleration potential.

Herein, beam dose is given the units of number of clusters per unit area. However, beam dose may also include beam current and/or time (e.g., GCIB dwell time). For example, the beam current may be measured and maintained constant, while time is varied to change the beam dose. Alternatively, for example, the rate at which clusters strike the surface of the substrate per unit area (i.e., number of clusters per unit area per unit time) may be held constant while the time is varied to change the beam dose.

The GCIB is irradiated onto at least a portion of the surface of the substrate with or without using a mask layer to etch at least part of the second layer 13A on the substrate 11 to form the contact via 15C.

The methods described in FIG. 2 and FIG. 4 may further include altering the one or more target etch process metrics to create one or more new target etch process metrics, and setting one or more additional GCIB properties of an additional GCIB process condition for the GCIB to achieve the one or more new target etch process metrics.

According to another embodiment, in addition to irradiation of the substrate 11 with the GCIB, another GCIB may be used for additional control and/or function. Irradiation of the substrate 11 by another GCIB, such as a second GCIB, may proceed before, during, or after use of the GCIB. For example, another GCIB may be used to dope a portion of the substrate 11 with an impurity. Additionally, for example, another GCIB may be used to modify a portion of the substrate 11 to alter properties of substrate 11. Additionally, for example, another GCIB may be used to etch a portion of the substrate 11 to remove additional material from substrate 11. Additionally, for example, another GCIB may be used to clean a portion of the substrate 11 to remove additional material or residue, such as halogen-containing residue, from substrate 11. Additionally yet, for example, another GCIB may be used to grow or deposit material on a portion of the substrate 11. The doping, modifying, etching, cleaning, growing, or depositing may comprise introducing one or more elements selected from the group consisting of He, Ne, Ar, Xe, Kr, B, C, Se, Te, Si, Ge, N, P, As, O, S, F, CI, and Br.

According to another embodiment, at least one portion of substrate 11 subjected to GCIB irradiation may be cleaned before or after the irradiating with the GCIB. For example, the cleaning process may include a dry cleaning process and/or a wet cleaning process. Additionally, the at least one portion of substrate 11 subjected to GCIB irradiation may be annealed after the irradiating with the GCIB.

According to another embodiment, when preparing and/or etching substrate 11, any portion of substrate 11, or the contact via/contact via pattern, may be subjected to corrective processing. During corrective processing, metrology data may be acquired using a metrology system coupled to a GCIB processing system, either in-situ or ex-situ. The metrology system may comprise any variety of substrate diagnostic systems including, but not limited to, optical diagnostic systems, X-ray fluorescence spectroscopy systems, four-point probing systems, transmission-electron microscope (TEM), atomic force microscope (AFM), scanning-electron microscope (SEM), etc. Additionally, the metrology system may comprise an optical digital profilometer (ODP), a scatterometer, an ellipsometer, a reflectometer, an interferometer, or any combination of two or more thereof.

For example, the metrology system may constitute an optical scatterometry system. The scatterometry system may include a scatterometer, incorporating beam profile ellipsometry (ellipsometer) and beam profile reflectometry (reflectometer), commercially available from KLA-Tencor Corporation, (One Technology Drive, Milpitas, Calif. 95035), or Nanometrics, Inc. (1550 Buckeye Drive, Milpitas, Calif. 95035). Additionally, for example, the in-situ metrology system may include an integrated Optical Digital Profilometry (iODP) scatterometry module configured to measure metrology data on a substrate.

The metrology data may include parametric data, such as geometrical, mechanical, electrical and/or optical parameters associated with the substrate, any layer or sub-layer formed on the substrate, and/or any portion of a device on the substrate. For example, metrology data can include any parameter measurable by the metrology systems described above. Additionally, for example, metrology data can include a film thickness, a surface and/or interfacial roughness, a surface contamination, a feature depth, a trench depth, a via depth, a feature width, a trench width, a via width, a critical dimension (CD), an electrical resistance, or any combination of two or more thereof.

The metrology data may be measured at two or more locations on the substrate. Moreover, this data may be acquired and collected for one or more substrates. The one or more substrates may, for instance, include a cassette of substrates. The metrology data is measured at two or more locations on at least one of the one or more substrates and may, for example, be acquired at a plurality of locations on each of the one or more substrates. Thereafter, the plurality of locations on each of the plurality of substrates can be expanded from measured sites to unmeasured sites using a data fitting algorithm. For example, the data fitting algorithm can include interpolation (linear or nonlinear) or extrapolation (linear or nonlinear) or a combination thereof.

Once metrology data is collected for the one or more substrates using the metrology system, the metrology data is provided to a controller for computing correction data. Metrology data may be communicated between the metrology system and the controller via a physical connection (e.g., a cable), or a wireless connection, or a combination thereof. Additionally, the metrology data may be communicated via an intranet or Internet connection. Alternatively, metrology data may be communicated between the metrology system and the controller via a computer readable medium.

Correction data may be computed for location specific processing of the substrate. The correction data for a given substrate comprises a process condition for modulation of the GCIB dose as a function of position on the substrate in order to achieve a change between the parametric data associated with the incoming metrology data and the target parametric data for the given substrate. For example, the correction data for a given substrate can comprise determining a process condition for using the GCIB to correct a non-uniformity of the parametric data for the given substrate. Alternatively, for example, the correction data for a given substrate can comprise determining a process condition for using the GCIB to create a specifically intended non-uniformity of the parametric data for the given substrate.

Using an established relationship between the desired change in parametric data and the GCIB dose and an established relationship between the GCIB dose and a GCIB process condition having a set of GCIB processing parameters, the controller determines correction data for each substrate. For example, a mathematical algorithm can be employed to take the parametric data associated with the incoming metrology data, compute a difference between the incoming parametric data and the target parametric data, invert the GCIB processing pattern (i.e., etching pattern or deposition pattern or both) to fit this difference, and create a beam dose contour to achieve the GCIB processing pattern using the relationship between the change in parametric data and the GCIB dose. Thereafter, for example, GCIB processing parameters can be determined to affect the calculated beam dose contour using the relationship between the beam dose and the GCIB process condition. The GCIB processing parameters can include a beam dose, a beam area, a beam profile, a beam intensity, a beam scanning rate, or an exposure time (or beam dwell time), or any combination of two or more thereof.

Many different approaches to the selection of mathematical algorithm may be successfully employed in this embodiment. In another embodiment, the beam dose contour may selectively deposit additional material in order to achieve the desired change in parametric data.

The correction data may be applied to the substrate using a GCIB. During corrective processing, the GCIB may be configured to perform at least one of smoothing, amorphizing, modifying, doping, etching, growing, or depositing, or any combination of two or more thereof. The application of the corrective data to the substrate may facilitate correction of substrate defects, correction of substrate surface planarity, correction of layer thickness, or improvement of layer adhesion. Once processed to GCIB specifications, the uniformity of the substrate(s) or distribution of the parametric data for the substrate(s) may be examined either in-situ or ex-situ, and the process may be finished or refined as appropriate.

TABLE 1 GCIB Beam Process Acceleration Condition GCIB Composition Potential (kV) P-Cell A Ar 30 0 B 5%NF₃/N₂ 30 0 C 5%NF₃/N₂ 60 0 D 20%CHF₃/He 60 0 E 20%CHF₃/He + O₂ 60 0 F 10%C₂F₆/He 60 0 G 10%C₂HF₅/He 60 0 H 20%CF₄/He 60 0 I 4%Cl₂/He 30 0 J 4%Cl₂/He 60 40 K 4%Cl₂/He + O₂ 60 40 L 4%Cl₂/He + O₂ 60 0

Turning now to FIGS. 6A through 6L, exemplary data for etching material on a substrate is graphically depicted. In particular, exemplary data is provided for etching silicon oxide and silicon nitride relative to one another, as well as relative to silicon and/or other Si-containing or Ge-containing layers or substrate materials. The data is useful in illustrating the dependence of several important GCIB etching process metrics on GCIB parameters. And, the data is applicable to defining GCIB process conditions for contact via patterning.

FIG. 6A is a bar graph of a normalized etch rate of silicon dioxide (SiO₂) as a function of twelve (12) GCIB process conditions. The GCIB process conditions for the twelve (12) GCIB etch processes are provided in Table 1. The etch rate for each GCIB process condition is normalized by the etch rate using an Ar GCIB, which is listed as GCIB process condition “A” in Table 1.

In Table 1, each GCIB process condition provides a GCIB composition, a beam acceleration potential (kV), and a P-Cell value that relates to modification of the beam energy distribution function. Concerning the GCIB composition, the notation “5% NF₃/N₂” represents the relative amount (mol/mol %) of NF₃ in N₂. Concerning the P-Cell value, as described above, the P-Cell value is related to a flow rate (in sccm, standard cubic centimeters per minute) of a background gas introduced to an increased pressure region to cause collisions between the GCIB and the background gas and, thus, broadening of the beam energy distribution function. For example, the pressure in the pressure cell, through which the GCIB traverses, is raised by introducing a background gas at a flow rate of 40 sccm (P-Cell value of “40”) (or a pressure-distance integral of about 0.005 torr-cm) to the pressure cell (the relationship for P-Cell value is approximately linear with pressure).

As illustrated in FIG. 6A, the etch rate of silicon dioxide (SiO₂) was determined for a wide range of GCIB process conditions. When the GCIB contains only Ar, as in GCIB process condition “A”, the etch rate is driven by a purely physical component, e.g., sputtering. However, FIG. 6A and Table 1 suggest that the GCIB composition may be selected to provide a chemical component to the etch process, and an increase in the etch rate.

As shown in FIG. 6B, a bar graph charts the etch selectivity between silicon dioxide (SiO₂) and photo-resist as a function of the GCIB process conditions in Table 1. The etch selectivity relates the etch rate of silicon dioxide (SiO₂) to the etch rate of photo-resist (P.R.) (i.e., E/R SiO₂/E/R P.R.). Inspection of FIG. 6B indicates that a CHF₃-based GCIB composition and a Cl₂-based GCIB composition provide an etch selectivity in excess of unity.

FIG. 6C is a data graph of etch rate of silicon dioxide (SiO₂) and photo-resist (P.R.) as a function of GCIB process condition and P-Cell value. The GCIB process conditions for three (3) GCIB etch processes are provided in Table 2. In Table 2, each GCIB process condition provides a GCIB composition, a beam acceleration potential (kV), and a flow rate (sccm) for each chemical component in the respective GCIB composition. As evident from FIG. 6C, the etch rate for both silicon dioxide and photo-resist using any of the three GCIB process conditions decreases as the P-Cell value is increased.

TABLE 2 Beam CHF₃/He O₂ Cl₂/He Acceleration Flow Rate Flow Rate Flow Rate GCIB Composition Potential (kV) (sccm) (sccm) (sccm) 20%CHF₃/He 60 400 0 0 20%CHF₃/He + O₂ 60 100 300 0 4%Cl₂/He 60 0 0 550

As shown in FIG. 6D, a bar graph charts the etch selectivity between silicon dioxide (SiO₂) and photo-resist as a function of the GCIB process conditions in Table 2. The etch selectivity relates the etch rate of silicon dioxide (SiO₂) to the etch rate of photo-resist (P.R.) (i.e., E/R SiO₂/E/R P.R.). Inspection of FIG. 6D indicates the following: (1) Etch selectivity between SiO₂ and P.R. increases with increasing P-Cell value; (2) Etch selectivity between SiO₂ and P.R. may slightly increase with oxygen addition in a halomethane composition, particularly at higher P-Cell value; and (3) CHF₃-based GCIB composition provides high etch selectivity between SiO₂ and P.R. than Cl₂-based GCIB composition.

As shown in FIG. 6E, a data graph of the surface roughness of the etch surface in silicon dioxide (SiO₂) is plotted as a function of the GCIB process condition in Table 2 and P-Cell value. The surface roughness (R_(a), measured in Angstrom, A) represents an average roughness. The degree of roughness may be a measure of the interfacial and/or surface unevenness. For example, the degree of roughness, such as surface roughness, may be characterized mathematically as a maximum roughness (R_(max)), an average roughness (R_(a)) (as shown in FIG. 6E), or a root-mean-square (rms) roughness (R_(q)). Inspection of FIG. 6E indicates the following: (1) Average roughness of SiO₂ surface decreases with increasing P-Cell value; and (2) CHF₃-based GCIB composition provides a slightly higher average roughness on SiO₂ than Cl₂-based GCIB composition.

As shown in FIG. 6F, a bar graph charts the etch rate of silicon dioxide (SiO₂) and the etch selectivity between silicon dioxide (SiO₂) and photo-resist as a function of the GCIB process conditions in Table 3. The etch selectivity relates the etch rate of silicon dioxide (SiO₂) to the etch rate of photo-resist (P.R.) (i.e., E/R SiO₂/E/R P.R.). The GCIB compositions for the three (3) GCIB process conditions in Table 3 are the same as in Table 2; however, some GCIB process conditions are adjusted to achieve relatively low surface roughness (of order magnitude of 3 Angstrom or less).

TABLE 3 Beam CHF₃/He O₂ Cl₂/He Etch Average Acceleration P-Cell Flow Rate Flow Rate Flow Rate Selectivity Roughness GCIB Composition Potential (kV) Value (sccm) (sccm) (sccm) (SiO₂/P.R.) (A) 20% CHF₃/He 60 40 300 0 0 3.3 3.0 20% CHF₃/He + O₂ 60 40 75 225 0 3.0 3.6 4% Cl₂/He 60 40 0 0 550 0.8 3.3

Table 3 provides the beam acceleration potential, the P-Cell value, the flow rates of each pressurized gas in the GCIB composition, and the resultant etch selectivity and average roughness. FIG. 6F displays the corresponding relative etch rate and etch selectivity. Clearly, the CHF₃-based GCIB composition achieves relatively low surface roughness with relatively high etch selectivity.

FIG. 6G is a bar graph of the etch selectivity for photo-resist (P.R.), silicon dioxide (SiO₂), and silicon nitride (SiN) relative to poly-crystalline silicon (Si) as a function of flow rate for a GCIB composition of 20% CHF₃/He. The GCIB process condition further includes a beam acceleration potential of 60 kV and a P-Cell value of 0. As the flow rate is increased from 350 sccm to 550 sccm, the etch selectivity for P.R., SiO₂, and SiN relative to Si decays from a value above unity to a value below unity.

FIG. 6H is a bar graph of the etch selectivity between silicon dioxide (SiO₂) and poly-crystalline silicon (Si) as a function of GCIB process condition for a GCIB composition of 10% CHF₃/He. As shown in FIG. 6H, an increase in P-Cell value increases the etch selectivity between SiO₂ and Si, while an increase in flow rate decreases the etch selectivity between SiO₂ and Si.

TABLE 4 Beam CHF₃/He CHF₃/O₂ O₂ He CHClF₂/He Etch Average Acceleration P-Cell Flow Rate Flow Rate Flow Rate Flow Rate Flow Rate Selectivity Roughness GCIB Composition Potential (kV) Value (sccm) (sccm) (sccm) (sccm) (sccm) (SiO₂/Si) (A) 20% CHF₃/He 60 40 350 0 0 0 0 6.4 2.5 20% CHF₃/He + O₂ 60 40 125 0 125 0 0 7.2 2.2 4% CHClF₂/He 60 40 0 0 0 0 680 9.1 4.0 10% CHF₃/O₂ 60 50 0 200 0 0 0 7.9 1.3 10% CHF₃/O₂ 60 40 0 230 0 0 0 6.6 2.7 10% CHF₃/O₂ + He 60 40 0 180 0 125 0 12.2 1.1 10% CHF₃/O₂ 30 40 0 300 0 0 0 3.7 8.4 20% CHF₃/He 30 40 475 0 0 0 0 1.1 3.9

In Table 4, several GCIB process conditions, and the resultant etch selectivity (between SiO₂ and Si) and average roughness are provided. The etch selectivity may be varied from a value of about 1 to about 12, while achieving an average roughness ranging from about 1 A to about 4 A, by adjusting various GCIB process conditions, including GCIB composition, beam acceleration potential, P-Cell value, and flow rate.

FIG. 6I is a data graph of the etch rate of SiO₂, the etch rate of poly-crystalline silicon (Si), and the etch selectivity between SiO₂ and Si as a function of the flow rate of He added to a GCIB composition of 10% CHF₃/O₂. The GCIB process condition for the peak value of etch selectivity (about 12.2) is provided in Table 4 (see row 6). While varying the He flow rate, the remaining parameters in the GCIB process condition were held constant.

FIG. 6J is a bar graph of the etch selectivity for photo-resist (P.R.), silicon dioxide (SiO₂), and silicon nitride (SiN) relative to poly-crystalline silicon (Si) as a function of P-Cell value for a GCIB composition of 10% CClF₃/He. The GCIB process condition further includes a beam acceleration potential of 60 kV and a flow rate of 450 sccm. As the P-Cell value is increased from 0 to 40, the etch selectivity for SiO₂ and SiN relative to Si increases, while the etch selectivity for P.R. relative to Si decreases.

TABLE 5 Beam CBrF₃/He N₂ Etch Average Acceleration P-Cell Flow Rate Flow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value (sccm) (sccm) (Si/SiO₂) Si (A) 10% CBrF₃/He 30 40 400 2.5 22.0 10% CBrF₃/He 30 0 351 2.3 19.1 10% CBrF₃/He 45 40 400 1.8 27.0 10% CBrF₃/He 60 40 400 1.4 28.0 10% CBrF₃/He 30 40 351 1.3 13.8 10% CBrF₃/He 30 40 350 0.9 18.0 10% CBrF₃/He 30 40 400 0.7 16.0 10% CBrF₃/He 60 20 350 0.6 8.7 10% CBrF₃/He 60 40 350 0.5 6.7 10% CBrF₃/He 60 40 151 350 0.5 6.7 10% CBrF₃/He 60 20 151 150 0.5 5.0 10% CBrF₃/He 60 40 175 175 0.5 3.7 10% CBrF₃/He 45 40 151 150 0.4 4.6 10% CBrF₃/He 60 40 151 250 0.4 4.6 10% CBrF₃/He 60 40 400 0.4 3.8 10% CBrF₃/He 60 40 150 150 0.4 3 10% CBrF₃/He 60 40 350 0.3

FIG. 6K is a bar graph of the etch selectivity for photo-resist (P.R.), silicon dioxide (SiO₂), and silicon nitride (SiN) relative to poly-crystalline silicon (Si) as a function of beam acceleration potential for a GCIB composition of 10% CClF₃/He. The GCIB process condition further includes a P-Cell value of 0 and a flow rate of 450 sccm. As the beam acceleration potential is decreased from 60 kV to 10 kV, the etch selectivity for P.R., SiO₂, and SiN relative to Si decreases.

In Table 5, several GCIB process conditions, and the resultant etch selectivity (between Si and SiO₂) and average roughness in Si are provided. Each GCIB process condition recites a GCIB composition containing 10% CBrF₃ in He. In some cases, N₂ is added to the GCIB. The etch selectivity may be varied from a value of about 0.3 to about 2.5, while achieving an average roughness ranging from about 3 A to about 30 A, by adjusting various GCIB process conditions, including GCIB composition, beam acceleration potential, P-Cell value, and flow rate. For example, N₂ addition coupled with increased beam acceleration potential, increased P-Cell value, and decreased flow rate of the etch compound produces the least average roughness.

TABLE 6 Beam CF₄/He Additive Etch Average Acceleration P-Cell Flow Rate Flow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value (sccm) (sccm) (Si/SiO₂) Si (A) 20% CF₄/He 30 0 451 0.54 14.1 20% CF₄/He 60 40 550 0.48 5.1 20% CF₄/He 60 0 451 0.47 18.6 20% CF₄/He 60 40 451 0.32 2.4

TABLE 7 Beam NF₃/N₂ Etch Etch Average Acceleration P-Cell Flow Rate Selectivity Selectivity Roughness- GCIB Composition Potential (kV) Value (sccm) (Si/SiN) (p-Si/SiN) Si (A) 20% NF₃/N₂ 30 10 500 3.8 31 20% NF₃/N₂ 30 40 500 3.8 20 20% NF₃/N₂ 60 10 750 3.5 60 20% NF₃/N₂ 30 50 450 3.2 3.4 16 20% NF₃/N₂ 60 10 500 2.7 33 20% NF₃/N₂ 60 10 500 2.4 35 20% NF₃/N₂ 45 10 400 2.3 2.3 30 20% NF₃/N₂ 45 10 350 1.8 1.9 22 20% NF₃/N₂ 45 50 450 1.7 1.8 15 20% NF₃/N₂ 45 30 350 1.5 1.6 15 20% NF₃/N₂ 30 40 350 1.5 11 20% NF₃/N₂ 45 30 400 1.4 1.5 17 20% NF₃/N₂ 60 10 500 1.4 26 20% NF₃/N₂ 60 50 500 1.3 17 20% NF₃/N₂ 60 10 500 1.3 24 20% NF₃/N₂ 45 40 350 1.2 10 20% NF₃/N₂ 45 50 350 1.2 1.3 8 20% NF₃/N₂ 45 50 400 1.1 1.4 10 20% NF₃/N₂ 60 10 250 1.1 11 20% NF₃/N₂ 60 40 250 0.9 2 20% NF₃/N₂ 60 40 250 0.9 3

In Table 6, several GCIB process conditions, and the resultant etch selectivity (between Si and SiO₂) and average roughness in Si are provided. Each GCIB process condition recites a GCIB composition containing 20% CF₄ in He. The etch selectivity may be varied from a value of about 0.32 to about 0.54, while achieving an average roughness ranging from about 2 A to about 19 A, by adjusting various GCIB process conditions, including GCIB composition, beam acceleration potential, P-Cell value, and flow rate.

TABLE 8 Beam Cl₂/N₂ Additive Etch Average Acceleration P-Cell Flow Rate Flow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value (sccm) (sccm) (Si/SiN) Si (A) 6% Cl₂/N₂ 10 0 350 8.2 92 6% Cl₂/N₂ 30 0 350 3.3 46 6% Cl₂/N₂ 10 0 425 8.7 6% Cl₂/N₂ 30 0 425 3.7 6% Cl₂/N₂ 10 0 500 10.7 6% Cl₂/N₂ 30 0 500 4.9 6% Cl₂/N₂ 60 40 350 3.3 32.5 6% Cl₂/N₂ 60 40 350 3.7 44 6% Cl₂/N₂ 60 25 350 3.3 6% Cl₂/N₂ 60 50 350 3.5 47.8 6% Cl₂/N₂ 60 50 450 5 69 6% Cl₂/N₂ 60 50 550 4.6 105 4% Cl₂/N₂ 60 50 225 125 (N₂) 2.7 16.6 6% Cl₂/N₂ 60 50 300  50 (He) 3.2 31 6% Cl₂/N₂ 30 50 350 5.3 83 2% Cl₂/N₂ 60 50 125 225 (N₂) 0.7 11.6 4% Cl₂/N₂ 60 50 225 125 (Ar) 3.5 34

In Table 7, several GCIB process conditions, and the resultant etch selectivity (between Si and SiN) and average roughness in Si are provided. Each GCIB process condition recites a GCIB composition containing 20% NF₃ in N₂. The etch selectivity may be varied from a value of about 1 to about 4, while achieving an average roughness ranging from about 2 A to about 60 A, by adjusting various GCIB process conditions, including GCIB composition, beam acceleration potential, P-Cell value, and flow rate. A high etch rate and etch selectivity may be achieved at the expense of average roughness. Furthermore, the etch selectivity between Si and SiN appears to be similar to the etch selectivity between p-doped Si and SiN.

In Table 8, several GCIB process conditions, and the resultant etch selectivity (between Si and SiN) and average roughness in Si are provided. Each GCIB process condition recites a GCIB composition containing 2%-6% Cl₂ in N₂. In some cases, He, Ar, or N₂ are added to the GCIB. The etch selectivity may be varied from less than unity to about 11, while achieving an average roughness ranging from about 12 A to about 105 A, by adjusting various GCIB process conditions, including GCIB composition, beam acceleration potential, P-Cell value, and flow rate.

In Table 9, several GCIB process conditions, and the resultant etch selectivity (between Si and SiN) and average roughness in Si are provided. Each GCIB process condition recites a GCIB composition containing 4%-6% Cl₂ in He. The etch selectivity may be varied from a value of about 1.4 to about 6, while achieving an average roughness ranging from about 5 A to about 40 A, by adjusting various GCIB process conditions, including GCIB composition, beam acceleration potential, P-Cell value, and flow rate. The use of He as a carrier for Cl₂ appears to produce lower average roughness than the use of N₂ as a carrier for Cl₂.

TABLE 9 Beam Cl₂/He Additive Etch Average Acceleration P-Cell Flow Rate Flow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value (sccm) (sccm) (Si/SiN) Si (A) 6% Cl₂/He 10 0 500 6.1 6% Cl₂/He 10 0 550 6.8 6% Cl₂/He 30 0 500 2.8 38.4 6% Cl₂/He 30 0 550 3.4 30.0 4% Cl₂/He 60 0 575 2 13.0 4% Cl₂/He 60 20 575 1.9 13.0 4% Cl₂/He 60 40 575 2.1 7.1 4% Cl₂/He 30 0 575 1.6 4% Cl₂/He 30 40 600 1.4 4.6

In Table 10, several GCIB process conditions, and the resultant etch selectivity (between Si and SiN) and average roughness in Si are provided. Each GCIB process condition recites a GCIB composition containing 35% HCl in He. The etch selectivity may be varied from a value of about 2 to about 7, while achieving an average roughness ranging from about 15 A to about 25 A, by adjusting various GCIB process conditions, including GCIB composition, beam acceleration potential, P-Cell value, and flow rate.

TABLE 10 Beam HCl/He Additive Etch Average Acceleration P-Cell Flow Rate Flow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value (sccm) (sccm) (Si/SiN) Si (A) 35% HCl/He 10 0 400 4.9 16.0 35% HCl/He 10 0 400 4.9 15.0 35% HCl/He 30 0 400 2.0 20.0 35% HCl/He 30 0 400 35% HCl/He 60 40 400 2.6 23.0 35% HCl/He 10 0 475 6.9 18.0 35% HCl/He 10 0 475 6.6 18.0 35% HCl/He 30 0 475 2.8 25.0 35% HCl/He 30 0 475 2.2 23.0

In FIG. 6L, exemplary data for etching material on a substrate is graphically depicted. FIG. 6L is a bar graph of etch rate of several materials, including NiFe, Cu, CoFe, Al, Al₂O₃, Ru, W, Mo, TaN, Ta, AlN, SiO₂, SiN, Si, SiC, photo-resist (P.R.), and SiCOH, for three (3) GCIB etch processes. The GCIB processes include: (A) Ar; (B) 5% NF₃/N₂; and (C) 4% Cl₂/He. The GCIB process conditions for the three (3) GCIB etch processes are provided in Table 11.

TABLE 11 GCIB Beam Flow Process Acceleration Rate Condition GCIB Composition Potential (kV) P-Cell (sccm) A Ar 30 0 250 B 5%NF₃/N₂ 30 0 500 C 4%Cl₂/He 30 0 700

In Table 11, each GCIB process condition provides a GCIB composition, a beam acceleration potential (kV), a P-Cell value that relates to modification of the beam energy distribution function, and a flow rate of the GCIB composition.

As illustrated in FIG. 6L, the etch rate of several metal-containing materials, such as CoFe, NiFe, and Al, tends to improve when using a Cl-based GCIB chemistry, as opposed to a F-based GCIB chemistry. Also, when the GCIB contains only Ar, as in GCIB process condition “A”, the etch rate is driven by a purely physical component, e.g., sputtering. However, FIG. 6L and Table 11 suggest that the GCIB composition may be selected to provide a chemical component to the etch process, and an increase in the etch rate.

According to another example, when etching an ONO layer to pattern a HAR contact via, the etching gas may include CHF₃. The etching gas may further include an oxygen-containing gas, such as O₂. As noted above, a CHF₃-based GCIB etching process can achieve the target etch process metrics noted above. The P-Cell value has been determined by the inventors to reduce corner rounding. For example, the P-Cell value may range from 15 to 80, or more preferably 20 to 70, or even more preferably 50 to 70 (e.g., a value of 60).

Referring now to FIG. 7, a GCIB processing system 100 for treating a substrate as described above is depicted according to an embodiment. The GCIB processing system 100 comprises a vacuum vessel 102, substrate holder 150, upon which a substrate 152 to be processed is affixed, and vacuum pumping systems 170A, 170B, and 170C. Substrate 152 can be a semiconductor substrate, a wafer, a flat panel display (FPD), a liquid crystal display (LCD), or any other workpiece. GCIB processing system 100 is configured to produce a GCIB for treating substrate 152.

Referring still to GCIB processing system 100 in FIG. 7, the vacuum vessel 102 comprises three communicating chambers, namely, a source chamber 104, an ionization/acceleration chamber 106, and a processing chamber 108 to provide a reduced-pressure enclosure. The three chambers are evacuated to suitable operating pressures by vacuum pumping systems 170A, 170B, and 170C, respectively. In the three communicating chambers 104, 106, 108, a gas cluster beam can be formed in the first chamber (source chamber 104), while a GCIB can be formed in the second chamber (ionization/acceleration chamber 106) wherein the gas cluster beam is ionized and accelerated. Then, in the third chamber (processing chamber 108), the accelerated GCIB may be utilized to treat substrate 152.

As shown in FIG. 7, GCIB processing system 100 can comprise one or more gas sources configured to introduce one or more gases or mixture of gases to vacuum vessel 102. For example, a first gas composition stored in a first gas source 111 is admitted under pressure through a first gas control valve 113A to a gas metering valve or valves 113. Additionally, for example, a second gas composition stored in a second gas source 112 is admitted under pressure through a second gas control valve 113B to the gas metering valve or valves 113. Further, for example, the first gas composition or second gas composition or both can include a condensable inert gas, carrier gas or dilution gas. For example, the inert gas, carrier gas or dilution gas can include a noble gas, i.e., He, Ne, Ar, Kr, Xe, or Rn.

Furthermore, the first gas source 111 and the second gas source 112 may be utilized either alone or in combination with one another to produce ionized clusters. The material composition can include the principal atomic or molecular species of the elements desired to react with or be introduced to the material layer.

The high pressure, condensable gas comprising the first gas composition or the second gas composition or both is introduced through gas feed tube 114 into stagnation chamber 116 and is ejected into the substantially lower pressure vacuum through a properly shaped nozzle 110. As a result of the expansion of the high pressure, condensable gas from the stagnation chamber 116 to the lower pressure region of the source chamber 104, the gas velocity accelerates to supersonic speeds and gas cluster beam 118 emanates from nozzle 110.

The inherent cooling of the jet as static enthalpy is exchanged for kinetic energy, which results from the expansion in the jet, causes a portion of the gas jet to condense and form a gas cluster beam 118 having clusters, each consisting of from several to several thousand weakly bound atoms or molecules. A gas skimmer 120, positioned downstream from the exit of the nozzle 110 between the source chamber 104 and ionization/acceleration chamber 106, partially separates the gas molecules on the peripheral edge of the gas cluster beam 118, that may not have condensed into a cluster, from the gas molecules in the core of the gas cluster beam 118, that may have formed clusters. Among other reasons, this selection of a portion of gas cluster beam 118 can lead to a reduction in the pressure in the downstream regions where higher pressures may be detrimental (e.g., ionizer 122, and processing chamber 108). Furthermore, gas skimmer 120 defines an initial dimension for the gas cluster beam entering the ionization/acceleration chamber 106.

The GCIB processing system 100 may also include multiple nozzles with one or more skimmer openings. Additional details concerning the design of a multiple gas cluster ion beam system are provided in U.S. Patent Application Publication No. 2010/0193701 A1, entitled “Multiple Nozzle Gas Cluster Ion Beam System” and filed on Apr. 23, 2009; and U.S. Patent Application Publication No. 2010/0193472 A1, entitled “Multiple Nozzle Gas Cluster Ion Beam Processing System and Method of Operating” and filed on Mar. 26, 2010; the contents of which are herein incorporated by reference in their entirety.

After the gas cluster beam 118 has been formed in the source chamber 104, the constituent gas clusters in gas cluster beam 118 are ionized by ionizer 122 to form GCIB 128. The ionizer 122 may include an electron impact ionizer that produces electrons from one or more filaments 124, which are accelerated and directed to collide with the gas clusters in the gas cluster beam 118 inside the ionization/acceleration chamber 106. Upon collisional impact with the gas cluster, electrons of sufficient energy eject electrons from molecules in the gas clusters to generate ionized molecules. The ionization of gas clusters can lead to a population of charged gas cluster ions, generally having a net positive charge.

As shown in FIG. 7, beam electronics 130 are utilized to ionize, extract, accelerate, and focus the GCIB 128. The beam electronics 130 include a filament power supply 136 that provides voltage V_(F) to heat the ionizer filament 124.

Additionally, the beam electronics 130 include a set of suitably biased high voltage electrodes 126 in the ionization/acceleration chamber 106 that extracts the cluster ions from the ionizer 122. The high voltage electrodes 126 then accelerate the extracted cluster ions to a desired energy and focus them to define GCIB 128. The kinetic energy of the cluster ions in GCIB 128 typically ranges from about 1000 electron volts (1 keV) to several tens of keV. For example, GCIB 128 can be accelerated to 1 to 100 keV.

As illustrated in FIG. 7, the beam electronics 130 further include an anode power supply 134 that provides voltage V_(A) to an anode of ionizer 122 for accelerating electrons emitted from ionizer filament 124 and causing the electrons to bombard the gas clusters in gas cluster beam 118, which produces cluster ions.

Additionally, as illustrated in FIG. 7, the beam electronics 130 include an extraction power supply 138 that provides voltage V_(EE) to bias at least one of the high voltage electrodes 126 to extract ions from the ionizing region of ionizer 122 and to form the GCIB 128. For example, extraction power supply 138 provides a voltage to a first electrode of the high voltage electrodes 126 that is less than or equal to the anode voltage of ionizer 122.

Furthermore, the beam electronics 130 can include an accelerator power supply 140 that provides voltage V_(ACC) to bias one of the high voltage electrodes 126 with respect to the ionizer 122 so as to result in a total GCIB acceleration energy equal to about V_(ACC) electron volts (eV). For example, accelerator power supply 140 provides a voltage to a second electrode of the high voltage electrodes 126 that is less than or equal to the anode voltage of ionizer 122 and the extraction voltage of the first electrode.

Further yet, the beam electronics 130 can include lens power supplies 142, 144 that may be provided to bias some of the high voltage electrodes 126 with potentials (e.g., V_(L1) and V_(L2)) to focus the GCIB 128. For example, lens power supply 142 can provide a voltage to a third electrode of the high voltage electrodes 126 that is less than or equal to the anode voltage of ionizer 122, the extraction voltage of the first electrode, and the accelerator voltage of the second electrode, and lens power supply 144 can provide a voltage to a fourth electrode of the high voltage electrodes 126 that is less than or equal to the anode voltage of ionizer 122, the extraction voltage of the first electrode, the accelerator voltage of the second electrode, and the first lens voltage of the third electrode.

Note that many variants on both the ionization and extraction schemes may be used. While the scheme described here is useful for purposes of instruction, another extraction scheme involves placing the ionizer and the first element of the extraction electrode(s) (or extraction optics) at V_(ACC). This typically requires fiber optic programming of control voltages for the ionizer power supply, but creates a simpler overall optics train. The invention described herein is useful regardless of the details of the ionizer and extraction lens biasing.

A beam filter 146 in the ionization/acceleration chamber 106 downstream of the high voltage electrodes 126 can be utilized to eliminate monomers, or monomers and light cluster ions from the GCIB 128 to define a filtered process GCIB 128A that enters the processing chamber 108. In one embodiment, the beam filter 146 substantially reduces the number of clusters having 100 or less atoms or molecules or both. The beam filter may comprise a magnet assembly for imposing a magnetic field across the GCIB 128 to aid in the filtering process.

Referring still to FIG. 7, a beam gate 148 is disposed in the path of GCIB 128 in the ionization/acceleration chamber 106. Beam gate 148 has an open state in which the GCIB 128 is permitted to pass from the ionization/acceleration chamber 106 to the processing chamber 108 to define process GCIB 128A, and a closed state in which the GCIB 128 is blocked from entering the processing chamber 108. A control cable conducts control signals from control system 190 to beam gate 148. The control signals controllably switch beam gate 148 between the open or closed states.

A substrate 152, which may be a wafer or semiconductor wafer, a flat panel display (FPD), a liquid crystal display (LCD), or other substrate to be processed by GCIB processing, is disposed in the path of the process GCIB 128A in the processing chamber 108. Because most applications contemplate the processing of large substrates with spatially uniform results, a scanning system may be desirable to uniformly scan the process GCIB 128A across large areas to produce spatially homogeneous results.

An X-scan actuator 160 provides linear motion of the substrate holder 150 in the direction of X-scan motion (into and out of the plane of the paper). A Y-scan actuator 162 provides linear motion of the substrate holder 150 in the direction of Y-scan motion 164, which is typically orthogonal to the X-scan motion. The combination of X-scanning and Y-scanning motions translates the substrate 152, held by the substrate holder 150, in a raster-like scanning motion through process GCIB 128A to cause a uniform (or otherwise programmed) irradiation of a surface of the substrate 152 by the process GCIB 128A for processing of the substrate 152.

The substrate holder 150 disposes the substrate 152 at an angle with respect to the axis of the process GCIB 128A so that the process GCIB 128A has an angle of beam incidence 166 with respect to a substrate 152 surface. The angle of beam incidence 166 may be 90 degrees or some other angle, but is typically 90 degrees or near 90 degrees. During Y-scanning, the substrate 152 and the substrate holder 150 move from the shown position to the alternate position “A” indicated by the designators 152A and 150A, respectively. Notice that in moving between the two positions, the substrate 152 is scanned through the process GCIB 128A, and in both extreme positions, is moved completely out of the path of the process GCIB 128A (over-scanned). Though not shown explicitly in FIG. 7, similar scanning and over-scan is performed in the (typically) orthogonal X-scan motion direction (in and out of the plane of the paper).

A beam current sensor 180 may be disposed beyond the substrate holder 150 in the path of the process GCIB 128A so as to intercept a sample of the process GCIB 128A when the substrate holder 150 is scanned out of the path of the process GCIB 128A. The beam current sensor 180 is typically a Faraday cup or the like, closed except for a beam-entry opening, and is typically affixed to the wall of the vacuum vessel 102 with an electrically insulating mount 182.

As shown in FIG. 7, control system 190 connects to the X-scan actuator 160 and the Y-scan actuator 162 through electrical cable and controls the X-scan actuator 160 and the Y-scan actuator 162 in order to place the substrate 152 into or out of the process GCIB 128A and to scan the substrate 152 uniformly relative to the process GCIB 128A to achieve desired processing of the substrate 152 by the process GCIB 128A. Control system 190 receives the sampled beam current collected by the beam current sensor 180 by way of an electrical cable and, thereby, monitors the GCIB and controls the GCIB dose received by the substrate 152 by removing the substrate 152 from the process GCIB 128A when a predetermined dose has been delivered.

In the embodiment shown in FIG. 8, the GCIB processing system 100′ can be similar to the embodiment of FIG. 7 and further comprise a X-Y positioning table 253 operable to hold and move a substrate 252 in two axes, effectively scanning the substrate 252 relative to the process GCIB 128A. For example, the X-motion can include motion into and out of the plane of the paper, and the Y-motion can include motion along direction 264.

The process GCIB 128A impacts the substrate 252 at a projected impact region 286 on a surface of the substrate 252, and at an angle of beam incidence 266 with respect to the surface of substrate 252. By X-Y motion, the X-Y positioning table 253 can position each portion of a surface of the substrate 252 in the path of process GCIB 128A so that every region of the surface may be made to coincide with the projected impact region 286 for processing by the process GCIB 128A. An X-Y controller 262 provides electrical signals to the X-Y positioning table 253 through an electrical cable for controlling the position and velocity in each of X-axis and Y-axis directions. The X-Y controller 262 receives control signals from, and is operable by, control system 190 through an electrical cable. X-Y positioning table 253 moves by continuous motion or by stepwise motion according to conventional X-Y table positioning technology to position different regions of the substrate 252 within the projected impact region 286. In one embodiment, X-Y positioning table 253 is programmably operable by the control system 190 to scan, with programmable velocity, any portion of the substrate 252 through the projected impact region 286 for GCIB processing by the process GCIB 128A.

The substrate holding surface 254 of positioning table 253 is electrically conductive and is connected to a dosimetry processor operated by control system 190. An electrically insulating layer 255 of positioning table 253 isolates the substrate 252 and substrate holding surface 254 from the base portion 260 of the positioning table 253. Electrical charge induced in the substrate 252 by the impinging process GCIB 128A is conducted through substrate 252 and substrate holding surface 254, and a signal is coupled through the positioning table 253 to control system 190 for dosimetry measurement. Dosimetry measurement has integrating means for integrating the GCIB current to determine a GCIB processing dose. Under certain circumstances, a target-neutralizing source (not shown) of electrons, sometimes referred to as electron flood, may be used to neutralize the process GCIB 128A. In such case, a Faraday cup (not shown, but which may be similar to beam current sensor 180 in FIG. 7) may be used to assure accurate dosimetry despite the added source of electrical charge, the reason being that typical Faraday cups allow only the high energy positive ions to enter and be measured.

In operation, the control system 190 signals the opening of the beam gate 148 to irradiate the substrate 252 with the process GCIB 128A. The control system 190 monitors measurements of the GCIB current collected by the substrate 252 in order to compute the accumulated dose received by the substrate 252. When the dose received by the substrate 252 reaches a predetermined dose, the control system 190 closes the beam gate 148 and processing of the substrate 252 is complete. Based upon measurements of the GCIB dose received for a given area of the substrate 252, the control system 190 can adjust the scan velocity in order to achieve an appropriate beam dwell time to treat different regions of the substrate 252.

Alternatively, the process GCIB 128A may be scanned at a constant velocity in a fixed pattern across the surface of the substrate 252; however, the GCIB intensity is modulated (may be referred to as Z-axis modulation) to deliver an intentionally non-uniform dose to the sample. The GCIB intensity may be modulated in the GCIB processing system 100′ by any of a variety of methods, including varying the gas flow from a GCIB source supply; modulating the ionizer 122 by either varying a filament voltage V_(F) or varying an anode voltage V_(A); modulating the lens focus by varying lens voltages V_(L1) and/or V_(L2); or mechanically blocking a portion of the GCIB with a variable beam block, adjustable shutter, or variable aperture. The modulating variations may be continuous analog variations or may be time modulated switching or gating.

The processing chamber 108 may further include an in-situ metrology system. For example, the in-situ metrology system may include an optical diagnostic system having an optical transmitter 280 and optical receiver 282 configured to illuminate substrate 252 with an incident optical signal 284 and to receive a scattered optical signal 288 from substrate 252, respectively. The optical diagnostic system comprises optical windows to permit the passage of the incident optical signal 284 and the scattered optical signal 288 into and out of the processing chamber 108. Furthermore, the optical transmitter 280 and the optical receiver 282 may comprise transmitting and receiving optics, respectively. The optical transmitter 280 receives, and is responsive to, controlling electrical signals from the control system 190. The optical receiver 282 returns measurement signals to the control system 190.

The in-situ metrology system may comprise any instrument configured to monitor the progress of the GCIB processing. According to one embodiment, the in-situ metrology system may constitute an optical scatterometry system. The scatterometry system may include a scatterometer, incorporating beam profile ellipsometry (ellipsometer) and beam profile reflectometry (reflectometer), commercially available from KLA-Tencor Corporation, (One Technology Drive, Milpitas, Calif. 95035), or Nanometrics, Inc. (1550 Buckeye Drive, Milpitas, Calif. 95035).

For instance, the in-situ metrology system may include an integrated Optical Digital Profilometry (iODP) scatterometry module configured to measure process performance data resulting from the execution of a treatment process in the GCIB processing system 100′. The metrology system may, for example, measure or monitor metrology data resulting from the treatment process. The metrology data can, for example, be utilized to determine process performance data that characterizes the treatment process, such as a process rate, a relative process rate, a feature profile angle, a critical dimension, a feature thickness or depth, a feature shape, etc. For example, in a process for directionally depositing material on a substrate, process performance data can include a critical dimension (CD), such as a top, middle or bottom CD in a feature (i.e., via, line, etc.), a feature depth, a material thickness, a sidewall angle, a sidewall shape, a deposition rate, a relative deposition rate, a spatial distribution of any parameter thereof, a parameter to characterize the uniformity of any spatial distribution thereof, etc. Operating the X-Y positioning table 253 via control signals from control system 190, the in-situ metrology system can map one or more characteristics of the substrate 252.

In the embodiment shown in FIG. 9, the GCIB processing system 100″ can be similar to the embodiment of FIG. 7 and further comprise a pressure cell chamber 350 positioned, for example, at or near an outlet region of the ionization/acceleration chamber 106. The pressure cell chamber 350 comprises an inert gas source 352 configured to supply a background gas to the pressure cell chamber 350 for elevating the pressure in the pressure cell chamber 350, and a pressure sensor 354 configured to measure the elevated pressure in the pressure cell chamber 350.

The pressure cell chamber 350 may be configured to modify the beam energy distribution of GCIB 128 to produce a modified processing GCIB 128A′. This modification of the beam energy distribution is achieved by directing GCIB 128 along a GCIB path through an increased pressure region within the pressure cell chamber 350 such that at least a portion of the GCIB traverses the increased pressure region. The extent of modification to the beam energy distribution may be characterized by a pressure-distance integral along the at least a portion of the GCIB path, where distance (or length of the pressure cell chamber 350) is indicated by path length (d). When the value of the pressure-distance integral is increased (either by increasing the pressure and/or the path length (d)), the beam energy distribution is broadened and the peak energy is decreased. When the value of the pressure-distance integral is decreased (either by decreasing the pressure and/or the path length (d)), the beam energy distribution is narrowed and the peak energy is increased. Further details for the design of a pressure cell may be determined from U.S. Pat. No. 7,060,989, entitled “Method and apparatus for improved processing with a gas-cluster ion beam”; the content of which is incorporated herein by reference in its entirety.

Control system 190 comprises a microprocessor, memory, and a digital I/O port capable of generating control voltages sufficient to communicate and activate inputs to GCIB processing system 100 (or 100′, 100″), as well as monitor outputs from GCIB processing system 100 (or 100′, 100″). Moreover, control system 190 can be coupled to and can exchange information with vacuum pumping systems 170A, 170B, and 170C, first gas source 111, second gas source 112, first gas control valve 113A, second gas control valve 113B, beam electronics 130, beam filter 146, beam gate 148, the X-scan actuator 160, the Y-scan actuator 162, and beam current sensor 180. For example, a program stored in the memory can be utilized to activate the inputs to the aforementioned components of GCIB processing system 100 according to a process recipe in order to perform a GCIB process on substrate 152.

However, the control system 190 may be implemented as a general purpose computer system that performs a portion or all of the microprocessor based processing steps of the invention in response to a processor executing one or more sequences of one or more instructions contained in a memory. Such instructions may be read into the controller memory from another computer readable medium, such as a hard disk or a removable media drive. One or more processors in a multi-processing arrangement may also be employed as the controller microprocessor to execute the sequences of instructions contained in main memory. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions. Thus, embodiments are not limited to any specific combination of hardware circuitry and software.

The control system 190 can be used to configure any number of processing elements, as described above, and the control system 190 can collect, provide, process, store, and display data from processing elements. The control system 190 can include a number of applications, as well as a number of controllers, for controlling one or more of the processing elements. For example, control system 190 can include a graphic user interface (GUI) component (not shown) that can provide interfaces that enable a user to monitor and/or control one or more processing elements.

Control system 190 can be locally located relative to the GCIB processing system 100 (or 100′, 100″), or it can be remotely located relative to the GCIB processing system 100 (or 100′, 100″). For example, control system 190 can exchange data with GCIB processing system 100 using a direct connection, an intranet, and/or the Internet. Control system 190 can be coupled to an intranet at, for example, a customer site (i.e., a device maker, etc.), or it can be coupled to an intranet at, for example, a vendor site (i.e., an equipment manufacturer). Alternatively or additionally, control system 190 can be coupled to the Internet. Furthermore, another computer (i.e., controller, server, etc.) can access control system 190 to exchange data via a direct connection, an intranet, and/or the Internet.

Substrate 152 (or 252) can be affixed to the substrate holder 150 (or substrate holder 250) via a clamping system (not shown), such as a mechanical clamping system or an electrical clamping system (e.g., an electrostatic clamping system). Furthermore, substrate holder 150 (or 250) can include a heating system (not shown) or a cooling system (not shown) that is configured to adjust and/or control the temperature of substrate holder 150 (or 250) and substrate 152 (or 252).

Vacuum pumping systems 170A, 170B, and 170C can include turbo-molecular vacuum pumps (TMP) capable of pumping speeds up to about 5000 liters per second (and greater) and a gate valve for throttling the chamber pressure. In conventional vacuum processing devices, a 1000 to 3000 liter per second TMP can be employed. TMPs are useful for low pressure processing, typically less than about 50 mTorr. Although not shown, it may be understood that pressure cell chamber 350 may also include a vacuum pumping system. Furthermore, a device for monitoring chamber pressure (not shown) can be coupled to the vacuum vessel 102 or any of the three vacuum chambers 104, 106, 108. The pressure-measuring device can be, for example, a capacitance manometer or ionization gauge.

Referring now to FIG. 10, a section 300 of an ionizer (122, FIGS. 7, 8 and 9) for ionizing a gas cluster jet (gas cluster beam 118, FIGS. 7, 8 and 9) is shown. The section 300 is normal to the axis of GCIB 128. For typical gas cluster sizes (2000 to 15000 atoms), clusters leaving the gas skimmer (120, FIGS. 7, 8 and 9) and entering an ionizer (122, FIGS. 7, 8 and 9) will travel with a kinetic energy of about 130 to 1000 electron volts (eV). At these low energies, any departure from space charge neutrality within the ionizer 122 will result in a rapid dispersion of the jet with a significant loss of beam current. FIG. 10 illustrates a self-neutralizing ionizer. As with other ionizers, gas clusters are ionized by electron impact. In this design, thermo-electrons (seven examples indicated by 310) are emitted from multiple linear thermionic filaments 302 a, 302 b, and 302 c (typically tungsten) and are extracted and focused by the action of suitable electric fields provided by electron-repeller electrodes 306 a, 306 b, and 306 c and beam-forming electrodes 304 a, 304 b, and 304 c. Thermo-electrons 310 pass through the gas cluster jet and the jet axis and then strike the opposite beam-forming electrode 304 b to produce low energy secondary electrons (312, 314, and 316 indicated for examples).

Though (for simplicity) not shown, linear thermionic filaments 302 b and 302 c also produce thermo-electrons that subsequently produce low energy secondary electrons. All the secondary electrons help ensure that the ionized cluster jet remains space charge neutral by providing low energy electrons that can be attracted into the positively ionized gas cluster jet as required to maintain space charge neutrality. Beam-forming electrodes 304 a, 304 b, and 304 c are biased positively with respect to linear thermionic filaments 302 a, 302 b, and 302 c and electron-repeller electrodes 306 a, 306 b, and 306 c are negatively biased with respect to linear thermionic filaments 302 a, 302 b, and 302 c. Insulators 308 a, 308 b, 308 c, 308 d, 308 e, and 308 f electrically insulate and support electrodes 304 a, 304 b, 304 c, 306 a, 306 b, and 306 c. For example, this self-neutralizing ionizer is effective and achieves over 1000 micro Amps argon GCIBs.

Alternatively, ionizers may use electron extraction from plasma to ionize clusters. The geometry of these ionizers is quite different from the three filament ionizer described above but the principles of operation and the ionizer control are very similar. Referring now to FIG. 11, a section 400 of an ionizer (122, FIGS. 7, 8 and 9) for ionizing a gas cluster jet (gas cluster beam 118, FIGS. 7, 8 and 9) is shown. The section 400 is normal to the axis of GCIB 128. For typical gas cluster sizes (2000 to 15000 atoms), clusters leaving the gas skimmer (120, FIGS. 7, 8 and 9) and entering an ionizer (122, FIGS. 7, 8 and 9) will travel with a kinetic energy of about 130 to 1000 electron volts (eV). At these low energies, any departure from space charge neutrality within the ionizer 122 will result in a rapid dispersion of the jet with a significant loss of beam current. FIG. 11 illustrates a self-neutralizing ionizer. As with other ionizers, gas clusters are ionized by electron impact.

The ionizer includes an array of thin rod anode electrodes 452 that is supported and electrically connected by a support plate (not shown). The array of thin rod anode electrodes 452 is substantially concentric with the axis of the gas cluster beam (e.g., gas cluster beam 118, FIGS. 7, 8 and 9). The ionizer also includes an array of thin rod electron-repeller rods 458 that is supported and electrically connected by another support plate (not shown). The array of thin rod electron-repeller electrodes 458 is substantially concentric with the axis of the gas cluster beam (e.g., gas cluster beam 118, FIGS. 7, 8 and 9). The ionizer further includes an array of thin rod ion-repeller rods 464 that is supported and electrically connected by yet another support plate (not shown). The array of thin rod ion-repeller electrodes 464 is substantially concentric with the axis of the gas cluster beam (e.g., gas cluster beam 118, FIGS. 7, 8 and 9).

Energetic electrons are supplied to a beam region 444 from a plasma electron source 470. The plasma electron source 470 comprises a plasma chamber 472 within which plasma is formed in plasma region 442. The plasma electron source 470 further comprises a thermionic filament 476, a gas entry aperture 426, and a plurality of extraction apertures 480. The thermionic filament 476 is insulated from the plasma chamber 470 via insulator 477. As an example, the thermionic filament 476 may include a tungsten filament having one-and-a-half turns in a “pigtail” configuration.

The section 400 of the gas cluster ionizer comprises an electron-acceleration electrode 488 having plural apertures 482. Additionally, the section 400 comprises an electron-deceleration electrode 490 having plural apertures 484. The plural apertures 482, the plural apertures 484, and the plural extraction apertures 480 are all aligned from the plasma region 442 to the beam region 444.

Plasma forming gas, such as a noble gas, is admitted to the plasma chamber 472 through gas entry aperture 426. An insulate gas feed line 422 provides pressurized plasma forming gas to a remotely controllable gas valve 424 that regulates the admission of plasma forming gas to the plasma chamber 472.

A filament power supply 408 provides filament voltage (V_(F)) for driving current through thermionic filament 476 to stimulate thermo-electron emission. Filament power supply 408 controllably provides about 140 to 200 A (amps) at 3 to 5 V (volts). An arc power supply 410 controllably provides an arc voltage (V_(A)) to bias the plasma chamber 472 positive with respect to the thermionic filament 476. Arc power supply 410 is typically operated at a fixed voltage, typically about 35 V, and provides means for accelerating the electrons within the plasma chamber 472 for forming plasma. The filament current is controlled to regulate the arc current supplied by the arc power supply 410. Arc power supply 410 is capable of providing up to 5 A arc current to the plasma arc.

Electron deceleration electrode 490 is biased positively with respect to the plasma chamber 472 by electron bias power supply 412. Electron bias power supply 412 provides bias voltage (V_(B)) that is controllably adjustable over the range of from 30 to 400 V. Electron acceleration electrode 488 is biased positively with respect to electron deceleration electrode 490 by electron extraction power supply 416. Electron extraction power supply 416 provides electron extraction voltage (V_(EE)) that is controllable in the range from 20 to 250 V. An acceleration power supply 420 supplies acceleration voltage (V_(ACC)) to bias the array of thin rod anode electrodes 452 and electron deceleration electrode 490 positive with respect to earth ground. V_(ACC) is the acceleration potential for gas cluster ions produced by the gas cluster ionizer shown in section 400 and is controllable and adjustable in the range from 1 to 100 kV. An electron repeller power supply 414 provides electron repeller bias voltage (V_(ER)) for biasing the array of thin rod electron-repeller electrodes 458 negative with respect to V_(ACC). V_(ER) is controllable in the range of from 50 to 100 V. An ion repeller power supply 418 provides ion repeller bias voltage (V_(IR)) to bias the array of thin rod ion-repeller electrodes 464 positive with respect to V_(ACC). V_(IR) is controllable in the range of from 50 to 150 V.

A fiber optics controller 430 receives electrical control signals on cable 434 and converts them to optical signals on control link 432 to control components operating at high potentials using signals from a grounded control system. The fiber optics control link 432 conveys control signals to remotely controllable gas valve 424, filament power supply 408, arc power supply 410, electron bias power supply 412, electron repeller power supply 414, electron extraction power supply 416, and ion repeller power supply 418.

For example, the ionizer design may be similar to the ionizer described in U.S. Pat. No. 7,173,252, entitled “Ionizer and method for gas-cluster ion-beam formation”; the content of which is incorporated herein by reference in its entirety.

The ionizer (122, FIGS. 7, 8 and 9) may be configured to modify the beam energy distribution of GCIB 128 by altering the charge state of the GCIB 128. For example, the charge state may be modified by adjusting an electron flux, an electron energy, or an electron energy distribution for electrons utilized in electron collision-induced ionization of gas clusters.

Although only certain embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. 

What is claimed is:
 1. A method for patterning a layer at a bottom of a high aspect ratio feature of a substrate, comprising: providing the substrate having a first layer with a feature pattern therein overlying a second layer, wherein the feature pattern is characterized with an initial critical dimension (CD), an initial corner profile, and an aspect ratio of 5:1 or greater; and etching through at least a portion of the second layer at the bottom of the feature pattern to extend the feature pattern at least partially into the second layer while retaining a final CD within a threshold of the initial CD and a final corner profile within a threshold of the initial corner profile using a gas cluster ion beam (GCIB) etching process.
 2. The method of claim 1 wherein the etching of the second layer comprises: selecting target etch process metrics for the GCIB etching process selected from a group consisting of: an etch selectivity between the second layer and the first layer, the final CD of the feature pattern formed through the first layer, a surface roughness of an exposed surface of the first layer, and a surface roughness of an exposed surface of the second layer; and establishing a GCIB process condition that includes GCIB properties for the GCIB etching process to achieve the selected target etch process metrics.
 3. The method of claim 2, wherein the GCIB process condition is selected from a group consisting of: a process composition of at least one constituent in a GCIB composition, a flow rate of at least one constituent in the GCIB composition, a GCIB acceleration potential, a background gas pressure for an increased pressure region through which a GCIB passes, and a background gas flow rate for an increased pressure region through which the GCIB passes.
 4. The method of claim 1, wherein the aspect ratio of the feature pattern is greater than 10:1.
 5. The method of claim 1, wherein the threshold of the final CD retained within the initial CD is less than 10 percent.
 6. The method of claim 1, wherein the GCIB etching process comprises: holding the substrate securely within a reduced-pressure environment; forming the GCIB from a pressurized gas that includes an etching gas that includes a carbon (C) element, a hydrogen (H) element, and a halogen element; accelerating the GCIB to the reduced-pressure environment; and irradiating the accelerated GCIB onto at least a portion of the substrate to selectively etch the portion of the second layer.
 7. The method of claim 6, wherein the etching gas includes a mono-substituted halomethane, a di-substituted halomethane, a tri-substituted halomethane, and any combination of two or more thereof.
 8. The method of claim 6, wherein the etching gas includes CHF₃, CHCl₃, and/or CHBr₃.
 9. The method of claim 6, wherein the pressurized gas includes He, Ne, O₂, CO, CO₂, N₂, NO, NO₂, N₂O, NH₃, F₂, HF, SF₆, NF₃ and/or any combination of two or more thereof.
 10. The method of claim 1, wherein the first layer includes an oxide layer.
 11. The method of claim 1, wherein the first layer includes a nitride layer.
 12. The method claim 1, wherein the second layer includes an oxide-nitride-oxide (ONO) layer.
 13. The method of claim 12, wherein the ONO layer is a multi-layer film that includes silicon oxide and/or silicon nitride.
 14. The method of claim 1, wherein the aspect ratio of the feature pattern includes substantially no charging damage.
 15. The method of claim 1, further comprising: determining the threshold of the final CD based on a pre-determined value for a difference in the initial CD from the final CD and the threshold of the final corner profile based on a pre-determined value for a difference in the initial corner profile from the final corner profile.
 16. The method of claim 15, wherein the difference is calculated from a difference in a mid-level measurement of the initial CD from the final CD, wherein the mid-level measurement of the initial CD from the final CD is measured at approximately a mid-depth of the feature pattern.
 17. The method of claim 15, wherein the difference is calculated from a difference in a bottom measurement of the initial CD from the final CD, wherein the bottom measurement of the initial CD from the final CD is measured at approximately at a bottom depth of the feature pattern.
 18. The method of claim 15, wherein the difference is calculated from a difference in a top measurement of the initial CD from the final CD, wherein the top measurement of the initial CD from the final CD is measured at approximately at a top depth of the feature pattern.
 19. The method of claim 15, wherein the difference is calculated from a difference in top corner measurement of the initial CD from the final CD, wherein the top corner measurement of the initial CD from the final CD is measured at approximately at a depth for each top corner of the feature pattern.
 20. A method of controlling patterning a layer at a bottom of a high aspect ratio feature of a substrate, comprising: providing a substrate having a first layer with a feature pattern therein overlying a second layer, wherein the feature pattern is characterized with an initial critical dimension (CD), an initial corner profile and an aspect ratio of 5:1 or greater; configuring a gas cluster ion beam (GCIB) etching process based on target etch process metrics to control the GCIB etching process to retain a final CD within a threshold of the initial CD and a final corner profile within a threshold of the initial corner profile; and etching through at least a portion of the second layer at the bottom of the feature pattern to extend the feature pattern at least partially into the second layer using the GCIB etching process configured to the target etch process metrics. 